unify ICUNameProcessorRules and ICURuleLoader

There is no need for the additional layer of indirection that
the ICUNameProcessorRules class adds. The ICURuleLoader can
fill the database properties directly.

nominatim/tools/check_database.py

@@ -166,7 +166,7 @@ def check_tokenizer(_, config):
         return CheckState.FAIL, dict(msg="""\
             Cannot load tokenizer. Did the import finish sucessfully?""")
 
-    result = tokenizer.check_database()
+    result = tokenizer.check_database(config)
 
     if result is None:
         return CheckState.OK